Method of maintaining circulation in boilers



May 18 1926.

S. OTIS METHOD OF MAINTAINING CIRCULATION IN BOILERS I 1922 3 Sheets-Sheet 1 Filed August '22,

May 18 1926.

S. OTIS METHOD OF MAINTAINING CIRCULATION IN BOILERS eats-Sheet 2 S. OTIS METHOD OF MAINTAINING CIRCULATION IN BOILERS Filed August 22, 1922 3 Sheets-Sheet 5 Patented May 18, 192

Utll'lhiii STA'EE SPENCER OTIS, OF CHICAGO, ILLINOIS.

METHOD OF MAINTAINING- CIFIGULATION IN BOILERS.

Application filed August 22, 1922. Serial in); 583,595..

This invention relates to a means for keeping up internal circulation in steam boilers for the purpose of equalizing temperature throughout the boiler and dis-' lation is sluggish, temperatures are eXces-' 1 sive in some parts and low in others, and the steam tends to lodge upon the heating surfaces and develop insulation, subjecting the tubes to burning, and reducing steaming effect,

It has long been proposed to supply air to steam boilers, for the purpose of disengaging steam from water therein, but this has been done through means of a number of widely distributed streams of air which have no substantial influence upon the internal circulation of the boiler.

According to one feature of the present invention, air is forced into the boiler under a pressure suilicient to overcome the resistance imposed by internal pressure, and so localized and restricted that it will induce vigorous internal circulation of the contained water with consequent distribution of heat units and equalization of boiler temperature and dislodgment of gas envelopes which tend to form in certain localities. In the preferred arrangement, air is injected into the lower portion of the water leg immediately in front ofthe fire box and at such intermediate point therein as will cause the water to flow forwardly toward the point of discharge, thence'upwardly with the rising column of air, and thence back to the place where water first 40 comes under the influence of air, so that effective circulation will result. By so cating the air delivery, two main paths of circulation will be set up within the boiler from the upper portion of the rising column of air, namely, the path of circulation rearward over the crown sheet, and downward toward the mud rings and forward toward the point of air delivery, and another path of circulation forward from the upper end of the rising column of air, to the front end of the boiler, thence downwardly and rearwardly until the immediate zone of restricted air discharge is reached. According to another feature of the invention, the air pressure is developed from the steam pressure of the boiler to which the air is supplied, as for instance, by applying such steam to a pump actuating piston of sufficiently greater area than the air piston to force the air against the boiler pressure, so that the air pressure is automatically regulated to accord with the boiler pressure.

In order that the invention may be thoroughly understood, a locomotive boiler equipment functioning in accordance with the invention has been illustrated in theaccompanying drawings, in which Figure 1 is a side elevation of a locomotive having the improved air equipment;

Figure 2 is a vertical transverse section in the plane of the water leg immediately forward of the fire boX;

Figure 3 is a vertical longitudinal section of the rear portion of the boiler; and

Figure 4: is a horizontal section on the line l l of Figures 2 and 3.

1 represents a locomotive boiler constructed with water leg 2 immediately forward of its fire box 3 and with an elongated tube section 4 extending forwardly from said water leg 2. Owing to the large horizontal dimension relative to the vertical, internal circulation of the locomotive boiler is usually sluggish and imperfect and exists more or less restrictedly in vertical zones influenced by local heat distributingconditions The present invention proposes to induce general circulation through the locomotive also in directions largely transverse to the normal zones of circulation, by delivering air at selected points, the preferable point being at the air nozzle 5, which is in the lower part of the front water leg 2; such air delivery being not only restricted as to location but being of a nature which causes a current of water from the point of air discharge, of such force as will draw the water vigorously forward through the side water legs to the place of the rising column of water and in turn cause a rearward current of water over the crown sheet and thence downwardly into side water legs, as indicated by arrows in Figure 2 and in rear portions of Figures 3 and 4. Similarly the rise of water in front water leg 2 will induce vigorous flow rearward in the tube section 4 of the boiler which will be replaced by water flowing forwardly in the upper portion of said tube section and downwardly among the tubes thereof.

In order to maintain the supply of air at the discharge nozzle 5, any suitable means may be employed, but it is preferable to use a means readily actuated by steam available from the boiler which is to be boosted by air circulation, and to this end an air pump 6 is provided on the locomotive in driven relation to the piston of steam cylinder 7, the superficial area of the steam piston being sufiiciently greater than that of the air pump to overcome the pressure in the boiler; said steam cylinder being supplied by steam through a pipe 8 controlled by the throttle 9 within reach of the engineer.

If desired, some suitable means of heat exchange between exhaust steam from cylinder 7 and atmospheric air entering the pump 6 may be provided for in order to reduce loss of heat units in the operation of the pump.

Supply of air to the steam boiler by power derived from a portion 01 the steam generated within the boiler may be carried on with economy since the injected air more than compensates for the steam consumed, by adding its volume to the steam space. Moreover, in passing through water, the air assists in disengagement of the steam, and does so with efiiciency in a system such as here described, because the air not only keeps the boiler water in circulation but brings constantly changing portions thereof into steam disengaging relation with the rising column of air.

I claim:

1. In combination with a locomotive boiler having horizontally arranged fire tubes, a fire box at one end of said fire tubes and water legs surrounding the fire box; means for supplying air under pressure and an air conduit supplied thereby, discharging upwardly into the boiler and having a locus of discharge restricted to about the middle and bottom of the water leg which lies forwardly of the fire box and beneath the rear ends of the fire tubes and thereby adapted to induce internal boiler circulation through two general paths involving respectively, the water legs which surround the fire box and the water space which surrounds the fire tubes. I

2. In combination with a locomotive boil-- er having horizontally arranged fire tubes, a fire box at one end of said fire tubes and water legs surrounding the fire box; means for supplying air under pressure and an air conduit supplied thereby, discharging upwardly into the boiler and having a locus of discharge restricted to about the middle and bottom of the water leg which lies forwardly of the fire box and beneath the rear ends of the fire tubes and thereby adapted to induce internal boiler circulation through two general paths involving respectively, the water legs which surround the fire box and the water space which surrounds the fire tubes; the means for supplying air under pressure being actuated by a pressure medium supplied by the boiler and delivering directly to the point of air discharge within the boiler.

In combination with a locomotive boiler having a fire box and heating surfaces supplied with products of combustion from said fire box, means for maintaining circulation of water in said boiler and equalizing temperatures therein, which consists in means for supplying air under pressure, and a discharge for said air within the water space of the boiler, located at and restricted to a relatively cool place in the boiler, and presenting discharged air in a direction to displace water from said cool place and induce the incoming of water from other portions or the boiler, the boiler being otherwise free from stirring influences and circulation being thereby set up in the boiler while permitting transfer oi heat from the heating surraces.

Signed at Chicago, Illinois, this 7th day 01 August, 1922.

SPENCER OTIS. 

